[Tagging] [OSM-talk] connection between 2 islands

[Randy]

Simone Saviolo wrote:

>>On Tue, Dec 1, 2009 at 4:48 AM, Cartinus 
>><cartinus at xs4all.nl> wrote:
>>If one wants to show the width of the embankment, I think the more
>>correct thing to do would be to have the embaknkment be one closed
>>curve, perhaps also with area=yes attached. This however would have
>>the problem of getting the 'spikes' also at the beginning and the end.
>>Another option would be to add a tag "embankment_side =
>>left/right/both" with "both" being the default value.
>>
>>
>I think the closed embankment way would not be a good approach. In my
>example, the embankment refers to a strip of land that is level with the
>area at the south, and that is raised above the surrounding area that 
>slowly
>goes downhill; but after a few hundred meters it slowly goes up again, and
>the railway is level again. Imagine a valley with a viaduct, only in a
>smaller scale and with a "non-bridge" (sorry I can't be more precise; I 
>have
>no idea what the correct English name is). At both ends the embankment is
>actually level with the ground, and should not be marked as embankment
>IMHO.
>
>Simone

Your description is identical or similar to the definition of embankment 
in the US. Fill the valley with water, and you approximate the original 
situation that started this thread.

The term "embankment" defines the structure on which the road is built in 
the original example for this thread. It doesn't define the highway.

The term "causeway" would apply to the roadway itself, but a causeway can 
be on an embankment or it can be a long low bridge, for example, the Lake 
Pontchartrain Causeway 
http://en.wikipedia.org/wiki/Lake_Pontchartrain_Causeway


In the original example, of this thread, the highway could be tagged 
"highway=*, causeway=yes" (granted, causeway is not currently defined in 
the wiki other than as an abandoned draft, which I think took the wrong 
tack).

In addition, or instead, the land which the causeway is constructed on 
could be tagged as an area with "embankment=yes" or "man-made=embankment". 
I would not map the shoreline as continuous between the two islands. 
Keeping them, and the embankment as separate entities will simplify any 
name taggin? Plus, you have both man-made and natural shorelines. I would 
map the embankment as a closed way using nodes that are common with the 
closed islands at each end.

Alternately causeway could be more precisely defined as 
"causeway=embankment" or "causeway=bridge", if you are more interested in 
just mapping the way rather than micromapping the embankment.

On a low bridge causeway which has higher bridges for boat traffic, I 
would break the way at those points to define the higher bridges, 
bridge=yes, even though the total causeway is itself a bridge.

Anyone interested in refreshing the "Causeway" tag as a property proposal? 
I think the problem with the original was that it was set up as 
man-made=causeway rather than as a descriptive term of the highway itself, 
because the author didn't understand the difference between the highway 
and the structure it was built on.
-- 
Randy